Many nocturnally active animals alter their behavior and activity with changing light conditions in connection with the lunar cycle. In most cases two major selective forces explain these responses, either change in predation risk or in prey availability.

The ‘‘lunar phobia’’ or reduced activity of bats during full moon was thought to be that bats adjust their activity to avoid predators.

Bats that normally fly and hunt for their food under the trees or close to the surface of water are the most timid when it comes to the moon. The high-fliers were much braver and hardly changed their behavior when the moon is at its biggest and brightest.

Nobody knows for sure why bats tend to hide away when the moon is full, but it is most likely that the brighter light makes it easier for predators to spot the bats. Perhaps there is a good reason for their selenophobia (fear of full moons) after all.